Cervical Dilation Explained by an L&D Nurse

When a provider performs a vaginal exam, they are checking your cervix. Your cervix starts off closed, and then progresses to 10 centimeters. And then, ta-daaaaa—you eventually have a baby because the door is open enough to let the baby out!

So lets talk about vaginal exams…

Cervical POSITION

I always tell my patients to think of their cervix as if it’s a tunnel. The position of the tunnel is either posterior (the train is facing the back), midposition, or anterior (the train will come out the front). When you’re body is not ready for labor, your cervix is in a posterior position, as a protection mechanism. Any time anyone–or anything 😉 touches your cervix, you may have a very small amount of bleeding, because your cervix is very vascular. As your body begins to get ready for labor, your cervix will go into a midposition and then into an anterior position, because the baby comes out the front 😃

Cervical CONSISTENCY & EFFACEMENT

The walls of the tunnel (your cervix) can be firm, moderate, or soft. This is called cervical consistency. The effacement describes how thick your cervix is. Your cervix should start off thick, again as a protection mechanism. It’s thickness is kind of like the width of the short end of a credit card. But eventually, your cervix will thin out and be as thin as a piece of paper!

Cervical DILATION

When we perform a vaginal exam, we’re looking for your tunnel with two of our fingers side-by-side. If we’re able to get into the tunnel, we then see how far we can spread out our two fingers. This tells us how dilated you are. Originally, you start off closed, which is zero centimeters dilated. Your mucous plug is hiding the doorway to your tunnel (your cervix!).

So think of it like this (if your baby is head down)…

There’s your baby’s head, and then there’s a cushion of fluid between your baby’s head and your cervix. Every time you have a contraction, your baby’s head presses down onto your cervix to help your cervix dilate. Remember, your cervix needs to go from 0 to 10 to have a baby.

When we talk about inducing someone, it means they’re not in labor. When we talk about augmenting someone, it means they’re contracting, but they need medication in order to adequately dilate or adequately contract. So again, this means they’re not in active labor.

If your cervix is thick (the effacement) and hard (the consistency), you will really have to pound your cervix hard with contractions to get it to dilate. This may mean you will need different medications to help coax your cervix to dilate or to get your uterus to adequately contract. It also means that you have a greater risk of having a failed induction and of having a cesarean delivery. It also means you’re more likely to need assistance with your delivery, so your provider may have to put something on (a vacuum) or around (forceps) your baby’s head to help them come out. It also means that you’re more likely to have a longer labor. The list goes on! Talk to your provider about these risks 😉 The more dilated you are, the softer your cervix is, if your cervix is in a good position, and the thinner your cervix is the better chance you have of having a vaginal delivery. Active labor does all of these things, without medication.

So your physician or midwife may say that you’re 2/50/-3. The first number represents how dilated you are (remember, you’re trying to get to 10). The second number represents your effacement (the smaller the number, the thicker you are, you’re trying to get to 100). The third number represents your station. Not included in these numbers—your cervical position and consistency! The station of the baby is how low the baby is relative to a part of your pelvic bone. Don’t understand that? Don’t worry, almost every will say “minus 2.” As the number gets larger, the baby gets lower and lower until the baby is born. -3, -2, -1, 0, +1, +2 and so forth. What you really need to know is that you want to have the largest possible positive number before pushing your baby out 😃

And that’s cervical dilation explained by a labor and delivery nurse 😃

[…] is weighing the risks of induction with the risks of staying pregnant. If a woman's cervix is not "favorable" or "ripe," it means that we will have to do more things to get her cervix to dilate. Every day, a ton of women […]

[…] the risks of induction with the risks of staying pregnant. If a woman’s cervix is not “favorable” or “ripe,” it means that we will have to do more things to get her cervix to dilate. Every day, a ton of women […]

[…] of my first memories as an L&D nurse was of a patient coming into triage around 21 weeks 8 cm dilated with a bulging bag of water. The provider broke her bag of water right there in triage, with what […]

[…] with letting labor progress naturally. Because the patient was contracting adequately and making cervical change, Pitocin hadn’t even been mentioned. I had actually eaten breakfast and was planning on what to […]

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3 years ago

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Sarah

Very informative! Good read even though I am a RN

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2 years ago

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Amee

And given the inexact nature of the measurement and the non linear progression of majority of labor what you don’t explain is what if any evidence exists for the utility of this exam in actual clinical decision making. There is not much.